1. Field of the Invention
The present invention pertains to the art of screening systems and, more particularly, to a fully integrated portable screening system capable of scanning for various analytes of interest, such as explosives and other trace compounds.
2. Discussion of the Prior Art
Since Sep. 11, 2001, protection against terrorist threats has become a national priority. This priority extends from the protection of government facilities inside the U.S. and abroad to the protection of private businesses and venues. Various types of threats have been postulated, including attacks using explosives, chemical and/or biological agents and nuclear and radiological agents (dirty bombs). The diversity of these threats has created a number of complex security challenges for national, state, and local governments, the transportation industry, private businesses, and even individuals. Total expenditures related to Homeland Security topped $100B in 2003 and billions more have been allocated in Federal, Supplemental Appropriations and State/Local spending. Increasingly, U.S. businesses are devoting more revenue to security systems, with total expenditures reaching tens of billions of dollars. Growth in the homeland security industry is expected to be vigorous over the next decade. Motivated by the wide diversity of potential threats and by the inadequacy of currently available systems, government investments in research and development are on the rise.
Of the various potential threats, explosives remain the number one choice of most terrorists. Indeed, many experts have noted that, in the case of terrorist activity, compelling statistical evidence indicates that bombs are a primary threat. The pernicious and prevalent nature of this threat has been observed in recent attacks on military, civilian and private sector targets. In particular, bombs, or improvised explosive devices (IEDs), have become a major threat to U.S. military operations. IED attacks against U.S. and coalition led forces in Iraq have been responsible for more military and civilian casualties than any other single weapon. The diversity, deadliness and increasingly prevalent use of IEDs in such conflicts highlight the low risk and high payoff nature of the weapon. Notably, most of the currently proposed methods for combating this threat involve systems that attempt to detect the IED after deployment. This is the least optimum time to deal with the threat as the signature of the IED and the vulnerability of the enemy is never lower than after the IED has been deployed. Further, the technical demands on such systems are increasingly high, environmental clutter creates unacceptably high false alarm rates. Moreover, once an IED is deployed, the probability of detection must be near perfect. Thus, there is a compelling need for systems that can detect bombers, bomb makers and bomb making factories in these diverse settings prior to the deployment of the weapon. In order to be most effective, the systems should be portable, inexpensive and easy to use.
Most currently available explosive detection methods involve costly, large, fixed base and low throughput systems. Current systems can cost more than one million dollars per portal for bulk explosive detection and tens of thousands of dollars for trace explosive detection. Indeed, these systems are so costly and operator intensive that they are of limited utility for widespread distributed operations and are therefore most often used at choke points or portals. Existing and recently developed systems, which were designed to increase portability, are expensive and power intensive. Perhaps more importantly, these systems were not designed with the primary purpose of detecting bombers, bomb makers and bomb making factories, the detection of which would have a far greater impact on the overall use of IEDs than finding any single device.
Existing systems are designed to detect vapor emanating from explosives or traces of explosives rather than the direct detection of explosive particulates. As explosives have very low vapor pressures, the vapor signature emanating from an explosive can be exceedingly small thus driving systems to ultra-high sensitivity requirements which result in significant false alarm rates. In some cases, heating is required to create an increased vapor signature. In order to identify bombers and bomb makers, a detection system should be focused on sampling methods that maximize the probability of identifying individuals that have been in extensive contact with explosives or in explosive contaminated areas.
In summary, currently available screening systems, in particular, explosive screening systems, suffer from many disadvantages, such as high cost, low throughput, high false alarm rates, operational complexity high maintenance and training requirements, poorly designed sampling methods, high power requirements and the like. In addition, these systems are most typically designed to identify the bomb itself, not the bombers or the bomb maker. They are expensive and cumbersome, thereby not being well-suited for deployment in a wide variety of field settings. These limitations have created a significant barrier to conducting widespread explosive screening which is necessary to combat the threat.
Based on the above, there is a great and urgent need for a deployable, portable and low cost screening system having a sampling system designed to detect trace contamination on people and objects associated with certain people, while being capable of use in a variety of field settings.